From ead2fe5eef5b2a90ffe64a7b2979eb3345417e72 Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Sat, 9 Dec 2017 21:28:09 -0500
Subject: [PATCH] handle empty classes - fixes #978

---
 src/css/Selector.ts                       |  1 +
 test/css/samples/empty-class/_config.js   | 20 ++++++++++++++++++++
 test/css/samples/empty-class/expected.css |  0
 test/css/samples/empty-class/input.html   |  7 +++++++
 4 files changed, 28 insertions(+)
 create mode 100644 test/css/samples/empty-class/_config.js
 create mode 100644 test/css/samples/empty-class/expected.css
 create mode 100644 test/css/samples/empty-class/input.html

diff --git a/src/css/Selector.ts b/src/css/Selector.ts
index c66034bccd..1ca0b240f2 100644
--- a/src/css/Selector.ts
+++ b/src/css/Selector.ts
@@ -229,6 +229,7 @@ function attributeMatches(node: Node, name: string, expectedValue: string, opera
 	const pattern = operators[operator](expectedValue, caseInsensitive ? 'i' : '');
 	const value = attr.value[0];
 
+	if (!value) return false;
 	if (value.type === 'Text') return pattern.test(value.data);
 
 	const possibleValues = new Set();
diff --git a/test/css/samples/empty-class/_config.js b/test/css/samples/empty-class/_config.js
new file mode 100644
index 0000000000..cf778c3401
--- /dev/null
+++ b/test/css/samples/empty-class/_config.js
@@ -0,0 +1,20 @@
+export default {
+	cascade: false,
+
+	warnings: [{
+		filename: "SvelteComponent.html",
+		message: "Unused CSS selector",
+		loc: {
+			line: 4,
+			column: 1
+		},
+		pos: 31,
+		frame: `
+			2:
+			3: <style>
+			4:   .x {
+			     ^
+			5:     color: red;
+			6:   }`
+	}]
+};
\ No newline at end of file
diff --git a/test/css/samples/empty-class/expected.css b/test/css/samples/empty-class/expected.css
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/test/css/samples/empty-class/input.html b/test/css/samples/empty-class/input.html
new file mode 100644
index 0000000000..b678a66739
--- /dev/null
+++ b/test/css/samples/empty-class/input.html
@@ -0,0 +1,7 @@
+<div class=""></div>
+
+<style>
+	.x {
+		color: red;
+	}
+</style>
\ No newline at end of file